The alleged on-going land reclamation of China at Subi reef is seen from Pagasa island (Thitu Island) in the Spratlys group of islands in the South China Sea, west of Palawan, Philippines, May 11, 2015. (Reuters Photo/Ritchie B. Tongo)

Manila. The military has blocked a group of lawmakers and security chiefs from visiting one of nine Philippine-held features in the disputed South China Sea due to safety issues, defense officials said on Friday (17/03).

But one senior Philippine general said the cancellation of this week's trip to Thitu Island, known locally as Pagasa, had more to do with concerns over how China would react.

Thitu is close to Subi Reef, one of seven manmade islands in the Spratlys that China is accused of militarizing with surface-to-air missiles, among other armaments.

The Philippines has squabbled with China for years over the South China Sea, but relations have improved under Philippine President Rodrigo Duterte, who will meet Chinese Vice Premier Wang Yang on Friday afternoon.

Five members of the House of Representatives were due to fly to Thitu on Thursday, while Defense Minister Delfin Lorenzana and military chief General Eduardo Ano were also planning a separate visit on Friday.

The lawmakers had planned to assess upgrades and new facilities needed for the Filipino fishing community of about 100 people living on the island in the Spratly archipelago.

The military said the trip was postponed due to "safety issues". Defense ministry spokesman Arsenio Andolong said landing on a porous runway after heavy rains was too dangerous.

"We will need at least five days of dry weather to harden and make it safe again for landing planes," he said. It was not clear when the trip would be rescheduled for.

But Lieutenant-General Raul del Rosario, who heads the Philippine Western Command, said there were concerns about how China would view the trip to Thitu.

"That is contested area, that is not 100 percent ours," he said in a Congressional hearing on Thursday. "That's why we are concerned if you fly there. Every time an aircraft flies there, it gets a warning and, there are times, they fire flares towards the aircraft."

The military declined to comment on Rosario's statement.

Maintaining and funding communities on islands in the Spratlys is seen by the Philippines and Vietnam as an essential measure in staking claims of sovereignty. China has soldiers on islands it occupies.

China claims most of the South China Sea, a strategic waterway through which about $5 trillion of goods passes each year. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims.

The Philippines has been wary of provoking China and wants to keep the peace and avoid jeopardizing billions of dollars of promised Chinese business deals and investments.